Hawking Radiation as Tunneling

Abstract

We present a short and direct derivation of Hawking radiation as a tunneling process, based on particles in a dynamical geometry. The imaginary part of the action for the classically forbidden process is related to the Boltzmann factor for emission at the Hawking temperature. Because the derivation respects conservation laws, the exact spectrum is not precisely thermal. We compare and contrast the problem of spontaneous emission of charged particles from a charged conductor.Comment: LaTeX, 10 pages; v2. journal version, added section on relation of black hole radiation to electric charge emission from a charged conducting sphere; v3. restored cut referenc